Attachment RF Exposure Study

This document pretains to SES-MOD-20180131-00076 for Modification on a Satellite Earth Station filing.

IBFS_SESMOD2018013100076_1332398

                       RADIATION HAZARD Exhibit
                          4.6 Meter 50 Watts




CBS has evaluated the radio frequency environment in and
around the proposed earth station and found it to be safe for
continuous exposure of operating personnel and the general
public.

Only the internal antenna structure, specifically the area
between the feedhorn and the dish, shows a radio frequency
environment that is considered excessive for continuous
exposure of personnel. This area is sufficiently high above
ground level that it cannot accidentally be entered without
the aid of mechanical equipment.

The supporting calculations that are submitted as part of
this study show that the proposed earth station is
environmentally safe, not only based on the criteria
published in the Occupational Safety and Health Act (OSHA),
but also in the light of recent recommendations for stricter
control of radio frequency radiation.

1.0   Station Parameters


                               Antenna Diameter     (D)   =         4 .6 M

                               Operating Wavelength       (A)   =      .021 M

                               Antenna Gain   (G)   =               55.4 dBi

                               Transmitter RF Power       (P)   = 50.0 W

2.0       Summary of Results

      RF Power Density — Centerline of Near Field = 0.722
mw/cm>*

      RF Power Density — Far Field =                          377 mw/cem*

      *RF Power Density — Edge of Near Field = 0.007 mw/cm>*

      *RF Power Density — Behind Antenna = 0.010 mw/cem


The density levels denoted by an asterisk are
representative of the maximum radiation environment in
or around the proposed earth station to which the
general public may be exposed.


.0   Near Field Evaluation


     The earth station antenna that will be employed for this
     service is designed to focus nearly all of the radiated
     radio frequency energy into a cylindrical beam with a
     diameter only slightly larger than that of the antenna
     dish.  Any intrusion into this beam would impair the
     performance of this earth station.  This broadcaster
     has, therefore, selected a site location for the antenna
     that will insure that the beam of principle radio
     frequency radiation is clear of any obstructions,
     buildings, etc. and cannot accidentally be entered by
     the general public.

&1   The near field cylindrical projection extends to a
     distance (d) that is defined by the following
     relationship:

                           d (nf)= D2/4X

                           d (ff)= .6D2 /A

     For the proposed antenna,     the near field extends,
     therefore,   to a distance of:


                           259.9 meters

     And the far field extends,    therefore,   to a distance of:

                           604.6 meters

&2   The maximum radio frequency power density within this
     near field cylinder is a function of the antenna
     diameter and transmitter power as follows:

                           W(nf)   = 9.6P/RmD

     For the proposed earth station, the maximum power
     density in the near field was computed not to exceed:

                             0 .722 mw/cm

&3   At the edge of the near field cylindrical beam, 0 .7
     antenna diameter removed from its center, the power
     density is attenuated at least 20 dB to 1/100th of the
     maximum near field power.  The power along the outside


edge of the beam will,   therefore,   not exceed:

                    0 .007 mw/em*


       Far Field Evaluation

       Beyond the near field region, the cylindrical beam
       begins to spread gradually into a slightly tapered cone
       in accordance with the published radiation pattern for
       the proposed antenna. The specified antenna gain is
       realized and the radiated power density decreases
       proportionally to the inverse square of distance from
       the antenna.

       For the purpose of determining the maximum power density
       within the far field, this broadcaster has
       conservatively assumed that the full antenna gain is
       already realized at the limit of the near field
       cylindrical region.  The radio frequency power density
       in the far field region is given by:

                              W(ff)      = PG/4md*

       For the proposed earth station, the maximum radiated
       power at the point of transition between the near field
       and far field regions was computed not to exceed:

                              0 .377 mw/em>

       Off—Axis Evaluation


       The proposed antenna meets or exceeds the performance
       specifications under part #25 of the FCC rules.  The
       off—axis gain of this antenna is, therefore, — 10dBi or
       less in any direction more than 48° removed from the
       centerline of the main bean.

       The off—axis power density may be conservatively
       evaluated using the far field method of computation:

                              W   (OA)    = 0.1P/4td*

       Assuming a distance of 2 meters from the antenna,   the
       density was calculated to be:

                              0 .010 mw/cem*
       Summary

6. 1   The computed values for near field projection distance,
       RF power density at the centerline, RF power density in


the far field, RF power density at the edge of the near
field, and RF power density behind the antenna are
furnished by the Engineering Department. Radiation
calculations verify that the actual levels do not exceed
the FCC OET 56 maximum of 5—mw/cm* with—in the off—axis
access areas of the systenm.



Document Created: 2019-04-14 08:41:01
Document Modified: 2019-04-14 08:41:01

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